Retractor mechanism for latch bolt

ABSTRACT

A retractor mechanism for the latch bolt in a cylindrical door lock set wherein the retractor comprises two parts, one part engaged with the latch bolt and a second part engageable by the knob spindles with means biasing said parts, at rest, to positions permitting a certain amount of lost motion by said second part, in response to spindle movement, before effective retraction of the latch bolt. The lost motion is calculated to insure that tilting of the spindles, as in response to a blow, cannot retract the latch bolt, while rotation of the spindles retracts the bolt in a normal manner.

[ 51 Dec.23, 1975 RETRACTOR MECHANISM FOR LATCH BOLT [75] Inventor: Lars Erickson, Clinton, Conn.

[73] Assignee: Walter Kidde & Co., Inc., Belleville,

221 Filed: July 19,1974

[2]] Appl. No.: 490,134

[52] US. Cl 292/169.22; 292/3365 [5|] Int. Cl. E05B 3/08; EOSC l/l2 [58] Field of Search 70/153, DIG. 42;

292/l69.2l, |69.22, 336.5, DIG. 52, DIG. 62

Primary E.raminerPaul R. Gilliam Assistant Examiner-Carl F. Pietruszka Attorney, Agent, or Firm-DeLio and Montgomery [57] ABSTRACT A retractor mechanism for the latch bolt in a cylindrical door lock set wherein the retractor comprises two parts, one part engaged with the latch bolt and a second part engageable by the knob spindles with means biasing said parts, at rest, to positions permitting a certain amount of lost motion by said second part, in response to spindle movement, before eifectiveretraction of the latch bolt. The lost motion is calculated to insure that tilting of the spindles, as in response to a blow, cannot retract the latch bolt, while rotation of the spindles retracts the bolt in a normal manner.

3 Claims, 6 Drawing Figures US. Patent Dec. 23, 1975 Sheet 1 of 2 3,927,905

Z Q0 5 2 0 0 0 W Z 334 5 7\ 4 I m. I! Z Kfi I w k 8 i 5 Wt m 90 9Q H M Q wh 5 I! 23 0O 7 Z 0 0 Z 2 1 Z N U.S. Patent Dec. 23, 1975 Sheet 2 012 3,927,905

RE'IRACTOR MECHANISM FOR LATCH BOLT This invention relates to the retractor mechanism for the latch bolt in a door lock adapted for actuation by rotation of knob spindles. Locks of the type referred to have a retractor slidable in a housing in a direction to retract the latch bolt to the unlocked position against a force biasing it toward locked position. Inner and outer know spindles have their rollbacks located adjacent retractor surfaces in positions to retract the bolt upon rotation of either spindle.

In a lock of this type the knob spindles are mounted in plain cylindrical bearings with sufficient clearance, initially, for easy rotation and with the probability that the looscness will increase with wear over a period of time. Rocking movement of the knob and spindle around a center within the bearing area can produce substantial movement of the rollback which is spaced some distance from the bearing and so has a lever arm which may magnify the lateral displacement of the knob. Locks having a retractor of integral construction, and in intimate contact with the rollback portions of the lock spindles, are prone to translation of that retractor in response to movement of the rollback when a moderate blow is imparted to the locked exterior knob. Such translation of the retractor (which engages the latch bolt assembly) may be sufficient to withdraw the latch bolt, without any axial rotation of rollback, particularly where the door and jamb are so spaced as to leave a substantial clearance.

It is an object of the present invention to provide a retractor mechanism wherein the retractor comprises two parts, one part engaged with the latch bolt and a second part engageable by the knob spindles, with means biasing said parts, at rest, to positions permitting a certain amount of lost motion by said second part, in response to spindle movement, before effective retraction of the latch bolt.

It is a further object of the invention to provide such a mechanism wherein the lost motion tilting of the knob spindles, as in response to a blow, cannot retract the latch bolt, while rotation of the spindles retracts the bolt in a normal manner.

It is another object of the invention to provide a two-piece retractor comprising forward and rear metal portions folded to have generally U-shaped axial sections and interlocked with their fold lines perpendicu lar.

It is a further object of the invention to provide a coupling between the knob, retractor and latch belt which includes a lost motion feature and wherein the presence of said feature is practically imperceptible either upon operation of the latch bolt or upon operation of the knob.

It is another object of the invention to provide certain improvements in the form, construction and arrangement of the several parts whereby the above-named and other objects may effectively be attained. The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth. and the scope of the invention will be indicated in the claims.

A practical embodiment of the invention is shown in the accompanying drawings, wherein;

FIG. 1 represents a horizontal sectional view, partly in plan, of a door lock assembly embodying the invention;

FIG. 2 represents a detail vertical section on the line ll-ll of FIG. I, with the retractor parts in their at-rest position;

FIG. 3 represents a detail vertical section, as in FIG. 2, with the outer knob rollback turned to take up the lost motion between the retractor parts;

FIG. 4 represents an elevational view of the forward part of the retractor;

FIG. 5 represents an elevational view of the rear part of the retractor, and

FIG. 6 represents a top plan view of the retractor parts in assembled relation.

Referring to the drawings, the lock assembly comprises a latch assembly 11, a central housing 12, and inner and outer knob assemblies I3, 14 all designed for installation in or cooperation with suitably formed cavities in a door, not shown.

The latch assembly I1 is of conventional construction, with a latch bolt 15 and dead bolt 16 mounted in a cylindrical shell 17, the latch bolt being urged toward latching position by the spring 18 and being retractable by forces applied to the T-shaped tail 19 which projects rearwardly from the shell 17.

Within the housing 12 is located the retractor, constituted by a forward part 20 and a rear part 2]. The forward part is generally U-shaped in section, the legs comprising straight parallel portions 22, slanting portions 23 and a flat end portion 24 provided with a rectangular slot 25, designed to receive and engage the tail I9 of the latch bolt (FIGS. 2 and 3). The legs 22 have extensions 26, each comprising a central stem and a pair of inwardly angled tabs 27, the edges of which are spaced from the adjacent edges of the legs 22 to leave two pairs of gaps 28. The rear part 21 is constituted by a bifurcated yoke having a flat wall 29, legs 30 bent at right angles to the wall 29 and leg extensions 31 bent again to lie parallel to the wall 29. The legs 30 are narrowed along their outer edges to leave stop surfaces 32, 33 at adjacent corners of the wall 29 and extensions 3t, respectively.

In order to assemble the parts 20,2] of the retractor, the forward part 20 is supplied 20, 2] its legs 22 diverging slightly; the tabs 27 are positioned to clear the edges of the legs 30 and the legs 22 are then closed to their parallel positions. This brings the corners of the legs 22 in line with the stop surfaces 32, 33 to limit compacting movement of the parts 20, 21 and the projection of tabs 27 into the path of the legs 20 limits expanding movement of the parts, while permitting a controlled amount of relative movement, according to a principal object of the invention. The spring guide 35 is a metal strip bent to a V-shape, with its upper ends turned outward and provided with tabs 36 which aid in stabilizing the upper ends of compression springs 37 in the assembly shown clearly in FIGS. 2 and 3, wherein the other ends of the springs rest against inturned ends 38 of the housing 12.

The door lock assembly of FIG. 1 includes a locking bar 40 adapted to be moved axially by means of the button 41 to effect releasable locking of the latch bolt and outer spindle in a manner which is well understood and forms no part of the present invention.

The retractor 20, 2I is actuated by means of the inner rollback 45 on the inner spindle 46, or the outer rollback 47 on the outer spindle 48, or the rollback 49 on the key spindle 50, the inner and outer rollbacks being in aligned positions within the forward part of the retractor and the key spindle rollback being within and concentric with the outer rollback. The working edges of the rollbacks, at rest (FIG. 2), lie adjacent to or in contact with the legs of the rear part 21 of the retractor. In this position, the part2] is urged forward by the springs 37 so that there is a gap Sl between the legs 30 and the adjacent edges of the tabs 27.

The inner spindle 47 has mounted thereon a knob 55 and the outer spindle 48, within which is the key spindle 50, has a corresponding knob 56, the spindles 46 and 48 being supported in cylindrical bearings 57, 58 respectively, and escutcheon plates 59, 60 being pro vided as is customary.

In operation, assuming the locking bar 40 to be inactive, the latch bolt can be retracted by actuation of any of the rollbacks 45, 47 or 49. The first small movement of a rollback causes the rear part 21 to move rearward, closing the gap 51, but not affecting at all the forward part 20 of the retractor until the position of FIG. 3 has been reached. When the legs 30 have come into contact with tabs 27 the two parts of the retractor move as one throughout the balance of the retraction stroke, drawing the latch bolt tail 19 rearward as far as necessary, and the springs 37 being compressed correspondingly. Since the entire movement of the rollback, before and after the forward part 20 has started moving, is made against the bias of the springs 37 the operation is quite smooth, i.e., the point where the rear part 21 starts to move the forward part 20 can scarcely be detected.

In a lock set having a one-piece retractor, a blow on the outer knob in the direction of the arrow A will transmit a shock in the opposite direction from the outer rollback to the retractor surface with which it is normally in contact, the knob-spindle-rollback assembly tending to pivot as a unit about a point within the adjacent bearing. If the shock is sharp enough, and particularly if the bearing is so loose as to permit a certain amplitude of movement, the retractor may draw the latch bolt back to an unlatched position. Such movement is initiated within the lock by movement of the rollback, so that the deadlatch, if any, is circumvented.

Where the two-piece retractor of the present invention is used, a blow on the outer knob may move the knob, spindle and rollback exactly asjust described but the only other part to be displaced is the rear part 21 of the retractor, which may move far enough to close some or all of the gap 5] but will be very unlikely to retract materially the forward part 20. The provision of this lost motion feature in the mechanical linkage between knobs and latch bolt thus effectively insulates the latter from blows against the former, and minimizes the danger of unauthorized entry by such means.

What I claim is:

1. In a door lock having a latch bolt and inner and outer knob spindles provided with rollbacks, a two-part retractor comprising a forward part in engagement with the latch bolt and rear part loosely engaged with the forward part to be relatively movable between forward and rearward positions, the forward part being generally U-shaped and provided near its ends with rearwardly and forwardly facing spaced stop surfaces defining a lost motion gap said stop surfaces lying in planes perpendicular to the direction of retractor movement, the rear part of the retractor having portions adapted to bear alternatively against said step surfaces, the size of the lost motion gap being a function of the spacing of said surfaces in said direction of retractor movement, and resilient means urging said rear part toward its forward position adjacent to both rollbacks and to said rearwardly facing stop surfaces, to open the said lost motion gap and enable the rear part to be moved rearward by either rollback without moving the forward part until said gap has been closed.

2. A door lock according to claim 1 wherein the end portions of said forward part are narrowed to form the rearwardly facing stop surfaces and are provided with rearwardly projecting extensions having angularly bent tabs to form the forwardly facing stop surfaces, a forward portion of the rear part of the retractor being disposed between said forwardly and rearwardly facing stop surfaces, which define the lost motion range of operation of said rear part.

3. A door lock according to claim 2 wherein the resilient means is adapted to urge said rear part toward a position in contact with said rearwardly facing stop surfaces, and the rollbacks are adapted in rotation to move said rear part against said forwardly facing stop surfaces of the forward part of the retractor so as to effect uniform rearward motion of both retractor parts. i t i 

1. In a door lock having a latch bolt and inner and outer knob spindles provided with rollbacks, a two-part retractor comprising a forward part in engagement with the latch bolt and rear part loosely engaged with the forward part to be relatively movable between forward and rearward positions, the forward part being generally U-shaped and provided near its ends with rearwardly and forwardly facing spaced stop surfaces defining a lost motion gap said stop surfaces lying in planes perpendicular to the direction of retractor movement, the rear part of the retractor having portions adapted to bear alternatively against said stop surfaces, the size of the lost motion gap being a function of the spacing of said surfaces in said direction of retractor movement, and resilient means urging said rear part toward its forward position adjacent to both rollbacks and to said rearwardly facing stop surfaces, to open the said lost motion gap and enable the rear part to be moved rearward by either rollback without moving the forward part until said gap has been closed.
 2. A door lock according to claim 1 wherein the end portions of said forward part are narrowed to form the rearwardly facing stop surfaces and are provided with rearwardly projecting extensions having angularly bent tabs to form the forwardly facing stop surfaces, a forward portion of the rear part of the retractor being disposed between said forwardly and rearwardly facing stop surfaces, which define the lost motion range of operation of said rear part.
 3. A door lock according to claim 2 wherein the resilient means is adapted to urge said rear part toward a position in contact with said rearwardly facing stop surfaces, and the rollbacks are adapted in rotation to move said rear part against said forwardly facing stop surfaces of the forward part of the retractor so as to effect uniform rearward motion of both retractor parts. 